KRAS is a new biomarker being used to select the best treatment for individual colorectal cancer (CRC) patients. The KRAS gene in a CRC
tumor may be 'wild-type' or 'mutant' and this KRAS 'status' will help determine which treatment the patient is given. This step-by-step guide
outlines the laboratory testing procedure used to determine KRAS status:
STEP 1:Before the KRAS test begins, a quality control check takes place in which the sample is evaluated by a pathologist to confirm that cancer cells are present
STEP 2:The tissue sample is then removed from the slide in order for the KRAS 'status' test to be performed
STEP 3:The tumor DNA from the tissue sample is purified
STEP 4: The tumor DNA is checked for purity as part of quality control procedures
STEP 5:A highly sensitive KRAS specific test, based on a polymerase chain reaction (PCR), uses labeled probes to amplify DNA in order to detect the presence of mutated KRAS
STEP 6:The products of the amplification are measured to determine whether the tumor has the wild-type KRAS gene or the mutant version. This enables a more targeted selection of treatments to be made for each patient, according to the KRAS status of their tumor
